Process for preparing 4-cyclohexyl-2-methyl-2-butanol

ABSTRACT

The present invention relates to a process for preparing 4-cyclohexyl-2-methyl-2-butanol. The process comprises the following steps:
     a) reaction of styrene with isopropanol at elevated temperature to obtain 4-phenyl-2-methyl-2-butanol, and   b) heterogeneously catalyzed hydrogenation of 4-phenyl-2-methyl-2-butanol over a catalyst suitable for ring hydrogenation of aromatics.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit (under 35 USC 119(e)) of U.S.Provisional application 61/316,870 filed Mar. 24, 2010 which isincorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a process for preparing4-cyclohexyl-2-methyl-2-butanol.

4-Cyclohexyl-2-methyl-2-butanol, which is also known as coranol, is afragrance with a lily-of-the-valley odor, the use of which as aconstituent of fragrance compositions was described for the first timein U.S. Pat. No. 4,701,278.

The preparation of 4-cyclohexyl-2-methyl-2-butanol was described by N.E. Okazawa et al. in Can. J. Chem. 60 (1982), 2180-93 and comprises theconversion of 3-cyclohexylpropanoic acid to the acid chloride, which isthen reacted with 2 mol of methyllithium to give4-cyclohexyl-2-methyl-2-butanol. Owing to the use of methyllithium, thispreparation process, especially in the case of performance on a largerscale, is afflicted with not inconsiderable risks and is economicallyunattractive. Nevertheless, no further preparation processes have beendescribed to date in the literature.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide aneconomically viable process for preparing4-cyclohexyl-2-methyl-2-butanol. This object is achieved by the processdescribed hereinafter, which comprises the following steps:

-   a) reaction of styrene with isopropanol at elevated temperature to    obtain 2-methyl-4-phenyl-2-butanol, and-   b) heterogeneously catalyzed hydrogenation of    2-methyl-4-phenyl-2-butanol over a catalyst suitable for ring    hydrogenation of aromatics.

A DETAILED DESCRIPTION OF THE INVENTION

The process can be represented by the following reaction scheme:

The invention thus relates to a process for preparing4-cyclohexyl-2-methyl-2-butanol with the steps described here andhereinafter and in the claims.

The process is associated with a series of advantages. It allows thepreparation of 4-cyclohexyl-2-methyl-2-butanol from very inexpensivecommodity chemicals. The use of expensive and hazardous reagents such asmethyllithium is not required. Both step a) and step b) can be performedwithout any problem on the industrial scale, and afford the particularproducts with high selectivity and good yields.

In step a) of the process according to the invention, isopropanol isreacted with styrene at elevated temperature. This forms2-methyl-4-phenyl-2-butanol in the manner of a hydroxyalkylation, andby-products including toluene and ethylbenzene, which can, however, beremoved from the target product, for example, by distillation.

In the context of an analytical study of the reaction of styrene withalkanols under supercritical conditions, the reaction was reported by T.Nakagawa et al. (see J. Supercritical Fluids, 27 (2003), p. 255-261 andTetrahedron Lett., 48 (2007), p. 8460-8463). However, the reaction wasnot utilized to preparatively obtain 2-methyl-4-phenyl-2-butanol.

With regard to the selectivity of the reaction, it has been found to beadvantageous when reaction in step a) is performed under supercriticalconditions. This is understood to mean reaction conditions under whichat least one of the components of the reaction mixture, preferably theisopropanol, is in the supercritical state. Accordingly, in a preferredembodiment of the process according to the invention, the reaction instep a) is effected under conditions under which isopropanol is in thesupercritical state. The critical temperature T_(c) of isopropanol is235° C.; the critical pressure P_(c) is 4.8 MPa. Supercriticalconditions can be established by the person skilled in the art byvarying pressure and temperature.

The temperature required for a sufficient rate of the reaction ofstyrene with isopropanol is generally at least 250° C., frequently atleast 300° C. and especially at least 320° C. To achieve a sufficientselectivity of the reaction, it has been found to be advantageous whenthe temperature of the reaction does not exceed a value of 500° C.,particularly 400° C. The reaction in step a) is effected preferably atelevated pressure, which is generally in the range from 5 to 50 MPa,frequently in the range from 10 to 30 MPa and especially in the rangefrom 15 to 25 MPa. The pressure in the reaction vessel can be adjustedby charging with an inert substance. The reaction is preferably effectedunder the autogenous pressure of the reaction mixture which exists atthe desired reaction temperature.

By its nature, the reaction time depends on the conditions selected andthe conversion desired, and is typically in the range from 30 sec to 4h, particularly in the range from 3 min to 3 h and especially in therange from 5 min to 2.5 h. In general, the reaction is conducted to suchan extent that the reactant used in deficiency, which is preferablystyrene, is converted to an extent of at least 80%, especially to anextent of at least 90%.

In one embodiment of the invention, the reaction time is in the rangefrom 30 min to 4 h, particularly in the range from 1 to 3 h andespecially in the range from 1.5 to 2.5 h. In general, the reaction isconducted to such an extent that the reactant used in deficiency, whichis preferably styrene, is converted to an extent of at least 80%,especially to an extent of at least 90%.

It has been found to be particularly advantageous to perform thereaction of step a) at elevated temperatures, i.e. above 300° C.,especially above 320° C., preferably in the range of 350° C. and 400° C.This allows short reaction times, which are typically in the range from30 sec to 30 min, particularly in the range from 3 min to 20 min andespecially in the range from 5 min to 15 min. In this way, even at ahigh styrene conversion, selectivities based on the target product ofdistinctly >60% can be achieved.

With regard to the selectivity of the reaction, it has been found to beadvantageous when the reaction in step a) is performed in substantial orcomplete absence of catalysts, for example free-radical initiators,acids or transition metal compounds. “Substantial absence” means thatthe concentration of any catalysts is less than 1 g/kg (<1000 ppm),especially less than 0.1 g/kg (<100 ppm), based on the total weight ofthe reaction mixture.

The reaction of styrene with isopropanol in step a) can be performed inbulk or in a suitable diluent, i.e. one which is inert under reactionconditions. Suitable inert diluents are aprotic organic solvents whichdo not have an ethylenically unsaturated double bond, for examplealiphatic and alicyclic ethers having preferably 4, 5 or 6 carbon atoms,aliphatic and cycloaliphatic saturated hydrocarbons having preferably 6to 8 carbon atoms, alkyl esters of aliphatic carboxylic acids havingpreferably 4 to 8 carbon atoms, and mixtures of the aforementionedsolvents. Preference is given to effecting the reaction in step a) insubstance, i.e. essentially no feedstocks other than styrene andisopropanol, for example inert solvents, are used for the reaction.“Essentially” means here that styrene and isopropanol make up at least95% by weight, especially at least 99% by weight, based on the totalamount of the components used in step a). In addition, the reactantsused for the reaction, i.e. styrene and isopropanol, as a result of thepreparation, may comprise small amounts of impurities such as water,ethylbenzene, toluene and the like, in which case the impuritiesgenerally make up less than 5% by weight, especially less than 1% byweight, based on the total amount of the reactants. In particular, thewater content of the reactants used in step a) is not more than 1% byweight, based on the total amount of the reactants.

With regard to the selectivity of the reaction, it has been found to beadvantageous when, in the reaction in step a), isopropanol is used in alarge excess, based on styrene, and/or it is ensured that a high excessof isopropanol, based on styrene present in the reaction zone, ispresent in the reaction zone in which styrene and isopropanol arecontacted with one another under reaction conditions. In general,styrene and isopropanol are reacted in step a) in a molar ratio ofstyrene to isopropanol of at most 1:5, preferably at most 1:10,especially at most 1:30, more preferably at most 1:40 and especially atmost 1:50. With regard to an efficient reaction regime, it isadvantageous when styrene and isopropanol are used in step a) in a molarratio in the range from 1:5 to 1:200, preferably in the range from 1:10to 1:200, especially in the range from 1:30 to 1:150 or in the rangefrom 1:30 to 1:130, more preferably in the range from 1:40 to 1:100 andespecially in the range from 1:50 to 1:90.

The reaction in step a) can be performed in batchwise mode, i.e. styreneand isopropanol are initially charged in a suitable reactor in thedesired molar ratio and brought to the desired reaction conditions andheld under reaction conditions until the desired conversion. Thereaction in step a) can also be performed in what is known assemibatchwise mode, i.e. the majority, generally at least 80%, of one orboth reactants is introduced into the reactor under reaction conditionscontinuously or in portions over a prolonged period, generally at least50% of the total reaction time. The reaction in step a) can also beperformed continuously, i.e. styrene and isopropanol are fedcontinuously into a reaction zone in the desired molar ratio and thereaction mixture is withdrawn continuously from the reaction zone. Therate at which styrene and isopropanol are supplied to the reaction zoneis guided by the desired residence time, which in turn depends in aknown manner on the reactor geometry and the above-specified reactiontime.

The reaction in step a) can in principle be performed in all reactorssuitable for the selected reaction conditions, preferably in autoclaves,which may have apparatus for mixing of the reactants, or in reactiontubes.

In order to keep the molar ratio of styrene to isopropanol low duringthe reaction and simultaneously to allow an efficient reaction regime,it has been found to be advantageous when at least 80%, especially atleast 90%, of the isopropanol used in step a) is initially charged,optionally together with a portion of the styrene, and at least 80%,especially at least 90%, of the styrene used in step a) is fed to thereaction in step a) under reaction conditions. The styrene can be addedin portions or preferably continuously. The rate at which styrene is fedin is preferably selected such that the molar ratio of the as yetunreacted styrene fed into the reaction zone or the reactor to theisopropanol present in the reaction zone during the reaction is lessthan 1:10, particularly not more than 1:40 and especially not more than1:50, for example in the range from <1:10 to 1:2000, preferably in therange from 1:40 to 1:1500 and especially in the range from 1:50 to1:1000. In a continuous reaction regime, styrene and isopropanol willtherefore preferably be supplied to the reactor or to the reaction zonein the aforementioned molar ratios. In a particular embodiment of theinvention, the rate with which styrene is supplied is preferablyselected such that the molar ratio of the styrene fed into the reactionzone or the reactor to the isopropanol present in the reaction zone isin the range from 1:10 to 1:130, particularly in the range from 1:20 to1:120, more preferably in the range from 1:40 to 1:100 and especially inthe range from 1:50 to 1:90. This is especially true, in the case of acontinuous reaction regime too, of the molar ratios of styrene andisopropanol supplied to the reactor or to the reaction zone.

The reaction mixture obtained in step a) can be worked up in a mannerknown per se or be used directly as such in step b) of the processaccording to the invention. In general, it has been found to beadvantageous to work up the reaction mixture obtained in step a), forexample by extraction or distillation or by a combination of thesemeasures. In one embodiment of the process according to the invention,the reaction mixture obtained in step a) is worked up by distillation toremove the desired 2-methyl-4-phenyl-2-butanol as the medium fractionfrom low and high boilers. When working with an isopropanol excess, thelow boiler fraction consisting predominantly of isopropanol can berecycled into the process. In general, isopropanol will be substantiallyremoved before step b), such that the proportion of isopropanol in thereactant used for hydrogenation in step b) is less than 20% by weight,especially not more than 10% by weight, based on the total amount ofreactant in step b).

According to the configuration of the distillation, puremethyl-4-phenyl-2-butanol is obtained (purity ≧95% by weight,particularly ≧98% by weight and especially ≧99% by weight or ≧99.5% byweight), or a composition which consists essentially, i.e. to an extentof at least 95% by weight, particularly at least 98% by weight andespecially at least 99% by weight or at least 99.5% by weight, of2-methyl-4-phenyl-2-butanol and small amounts of2-methyl-4-phenyl-2-pentanol, for example compositions in which theweight ratio of 2-methyl-4-phenyl-2-butanol to2-methyl-4-phenyl-2-pentanol is in the range from 50:1 to 1000:1. Boththe pure 2-methyl-4-phenyl-2-butanol and the composition which consistsessentially of 2-methyl-4-phenyl-2-butanol and small amounts of2-methyl-4-phenyl-2-pentanol can be used in the subsequent hydrogenationin step b), and give correspondingly pure4-cyclohexyl-2-methyl-2-butanol (purity≧95% by weight, particularly ≧98%by weight and especially±99% by weight or ≧99.5% by weight), or acomposition which consists essentially, i.e. to an extent of at least95% by weight, particularly at least 98% by weight and especially atleast 99% by weight or at least 99.5% by weight of4-cyclohexyl-2-methyl-2-butanol, and small amounts of4-cyclohexyl-2-methyl-2-pentanol, for example compositions in which theweight ratio of 4-cyclohexyl-2-methyl-2-butanol to4-cyclohexyl-2-methyl-2-pentanol is in the range from 50:1 to 1000:1.

The 2-methyl-4-phenyl-2-butanol obtained in step a) is subsequentlysubjected, in step b) of the process according to the invention, to aheterogeneously catalyzed hydrogenation over a catalyst suitable forring hydrogenation of aromatics, which is also referred to hereinafteras catalyst.

Suitable catalysts are in principle all catalysts known to be suitablefor ring hydrogenation of aromatics, i.e. catalysts which catalyze thehydrogenation of phenyl groups to cyclohexyl groups. These are typicallycatalysts which comprise at least one active metal from group VIIIB ofthe Periodic Table (CAS version), for example palladium, platinum,cobalt, nickel, rhodium, iridium, ruthenium, especially ruthenium,rhodium or nickel, or a mixture of two or more thereof, optionally incombination with one or more further active metals. Preferred furtheractive metals are selected from groups IB and VIIB of the Periodic Table(CAS version). Among the likewise usable metals of transition groups IBand/or VIIB of the Periodic Table of the Elements, for example, copperand/or rhenium are suitable.

The catalysts may be unsupported catalysts or preferably supportedcatalysts. Suitable support materials are, for example, activatedcarbon, silicon carbide, silicon dioxide, aluminum oxide, magnesiumoxide, titanium dioxide, zirconium dioxide, aluminosilicates andmixtures of these support materials. The amount of active metal istypically 0.05 to 10% by weight, frequently 0.1 to 7% by weight andespecially 0.1 to 5% by weight, based on the total weight of thesupported catalyst, especially when the active metal is a noble metalsuch as rhodium, ruthenium, platinum, palladium or iridium. In catalystswhich comprise cobalt and/or nickel as active metals, the amount ofactive metal may be up to 100% by weight and is typically in the rangefrom 1 to 100% by weight, especially 10 to 90% by weight, based on thetotal weight of the catalyst.

The supported catalysts can be used in the form of a powder. In general,such a powder has particle sizes in the range from 1 to 200 μm,especially 1 to 100 μm. Pulverulent catalysts are suitable especiallywhen the catalyst is suspended in the reaction mixture to behydrogenated (suspension mode). In the case of use of the catalysts infixed catalyst beds, it is customary to use shaped bodies, which mayhave, for example, the shape of spheres, tablets, cylinders, strands,rings or hollow cylinders, stars and the like. The dimensions of theseshaped bodies vary typically within the range from 0.5 mm to 25 mm.Frequently, catalyst extrudates with extrudate diameters of 1.0 to 5 mmand extrudate lengths of 2 to 25 mm are used. It is generally possibleto achieve higher activities with smaller extrudates, but thesetypically do not have sufficient mechanical stability in thehydrogenation process. Therefore, very particular preference is given tousing extrudates with extrudate diameters in the range from 1.5 to 3 mm.Likewise preferred are spherical support materials with sphere diametersin the range from 1 to 10 mm, especially 2 to 6 mm.

Preferred catalysts are those which comprise at least one active metalselected from ruthenium, rhodium and nickel, and optionally incombination with one or more further active metals selected from groupsIB, VIIB or VIIIB of the Periodic Table (CAS version).

Particularly preferred catalysts are ruthenium catalysts. These compriseruthenium as the active metal, optionally in combination with one ormore further active metals. Preferred further active metals are selectedfrom groups IB, VIIB or VIIIB of the Periodic Table (CAS version). Thecatalysts are unsupported catalysts or preferably supported catalysts.Examples of further active metals from group VIIIB are, for example,platinum, rhodium, palladium, iridium, cobalt or nickel, or a mixture oftwo or more thereof. Among the likewise usable metals of transitiongroups IB and/or VIIB of the Periodic Table of the Elements, forexample, copper and/or rhenium are suitable. Preference is given tousing, ruthenium alone as the active metal, or together with platinum oriridium as the active metal; very particular preference is given tousing ruthenium alone as the active metal.

Preference is given especially to ruthenium catalysts in which theruthenium is arranged on support material, called supported rutheniumcatalysts. The support materials of such supported catalysts generallyhave a BET surface area, determined by N₂ adsorption to DIN 66131, of atleast 30 m²/g, especially 50 to 1000 m²/g. Preference is given tosilicon dioxide-containing support materials, especially those whichhave a silicon dioxide content of at least 90% by weight, based on thetotal weight of the support material. Likewise preferred are aluminumoxide-containing support materials, especially those which have analuminum oxide content (calculated as Al₂O₃) of at least 90% by weight,based on the total weight of the support material.

Suitable ruthenium catalysts are the catalysts specified, for example,in U.S. Pat. No. 3,027,398, DE 4407019, EP 258789, EP 813906, EP1420012, WO 99/32427, WO 00/78704, WO 02/100536, WO 03/103830, WO2005/61105, WO 2005/61106, WO 2006/136541, and that specified in EP09179201.0, which was yet to be published at the priority date of thepresent application. With regard to the catalysts disclosed therein,reference is made to these documents.

Equally preferred catalysts are rhodium catalysts. These compriserhodium as an active metal, optionally in combination with one or morefurther active metals. Preferred further active metals are selected fromgroups IB, VIIB or VIIIB of the Periodic Table (CAS version). Thecatalysts may be unsupported catalysts or preferably supportedcatalysts. Examples of further active metals are from the group VIIIBare, for example, platinum, palladium, iridium, cobalt or nickel, or amixture of two or more thereof. Among the likewise useable metals oftransition groups IB and/or VIIB of the Periodic Table of the Elements,copper and/or rhenium, for example, are suitable. In these catalysts,preference is given to using rhodium alone as the active metal. Suitablerhodium catalysts are known, for example, from the publications citedabove for ruthenium catalysts, or can be prepared by the proceduresspecified therein, or are commercially available, for example thecatalyst Escat 34 from Engelhard.

Equally preferred catalysts are nickel catalysts. These comprise nickelas an active metal, optionally in combination with one or more furtheractive metals. Preferred further active metals are selected from groupsIB, VIIB or VIIIB of the Periodic Table (CAS version). The catalysts maybe unsupported catalysts or preferably supported catalysts. Examples offurther active metals are from the group VIIIB are, for example,platinum, palladium, iridium or cobalt, or a mixture of two or morethereof. Among the likewise useable metals of transition groups IBand/or VIIB of the Periodic Table of the Elements, copper and/orrhenium, for example, are suitable. In these catalysts, preference isgiven to using nickel alone as the active metal. Suitable nickelcatalysts are commercially available, for example BASF catalyst Ni5249P.

The catalyst used in step b) is more preferably a supported catalystwhich comprises, as an active metal, ruthenium alone or together with atleast one further active metal of transition groups IB, VIIB or VIIIB ofthe Periodic Table of the Elements (CAS version) on a support material.Preference is given to using ruthenium alone as the active metal ortogether with platinum or iridium as the active metal; very particularpreference is given to using ruthenium alone as the active metal. Usefulsupport materials for the supported ruthenium catalysts are in principlethe aforementioned support materials. Preference is given to silicondioxide-containing support materials, especially those which have asilicon dioxide content of at least 90% by weight, based on the totalweight of the support material. Preference is likewise given to aluminumoxide-containing support materials, especially those which have analuminum oxide content (calculated as Al₂O₃) of at least 90% by weight,based on the total weight of the support material. Preference is givento support materials having a specific BET surface area, determined byN₂ adsorption to DIN 66131, of at least 30 m²/g, especially 50 to 1000m²/g. The amount of active metal is typically 0.05 to 10% by weight,preferably 0.1 to 3% by weight and especially 0.1 to 1% by weight, basedon the total weight of the supported ruthenium catalyst.

Likewise preferably, the catalyst used in step b) is a supportedcatalyst which comprises, as an active metal, rhodium alone or togetherwith at least one further active metal of transition groups IB, VIIB orVIIIB of the Periodic Table of the Elements (CAS version) on a supportmaterial. Preference is given to using rhodium alone as the active metalor together with platinum or iridium as the active metal; veryparticular preference is given to using rhodium alone as the activemetal. Useful support materials for the supported rhodium catalysts arein principle the aforementioned support materials. Preference is givento silicon dioxide-containing support materials, especially those whichhave a silicon dioxide content of at least 90% by weight, based on thetotal weight of the support material. Preference is likewise given toaluminum oxide-containing support materials, especially those which havealuminum oxide content (calculated as Al₂O₃) of at least 90% by weight,based on the total weight of the support material. The amount of activemetal is typically 0.05 to 10% by weight, based on the total weight ofthe supported rhodium catalyst.

Likewise preferably, the catalyst used in step b) is a catalyst whichcomprises, as an active metal, nickel alone or together with at leastone further active metal of transition groups IB, VIIB or VIIIB of thePeriodic Table of the Elements (CAS version), optionally on a supportmaterial. Preference is given to using nickel alone as the active metal.Useful support materials for the supported nickel catalysts are inprinciple the aforementioned support materials. Preference is given tosilicon dioxide-, aluminum oxide- and magnesium oxide-containing supportmaterials, especially those which consist to an extent of at least 90%by weight of such materials. The amount of active metal is typically 1to 90% by weight, preferably 10 to 80% by weight and especially 30 to70% by weight, based on the total weight of the supported nickelcatalyst. Preference is also given to those nickel catalysts whichconsist essentially exclusively of active metal, i.e. wherein the amountof active metal is more than 90% by weight, e.g. 90 to 100% by weight.

In a particularly preferred embodiment, a shell catalyst is used,especially a shell catalyst which has, as the active metal, rutheniumalone or together with at least one further active metal of transitiongroups IB, VIIB or VIIIB of the Periodic Table of the Elements in theamounts specified above. Such shell catalysts are known especially fromWO 2006/136541, and in EP 09179201.0, which was yet to be published atthe priority date of the present application.

Such a shell catalyst is a supported catalyst wherein the predominantamount of the active metal(s) present in the catalyst is close to thesurface of the catalyst. In particular, at least 60% by weight, morepreferably at least 80% by weight, based in each case on the totalamount of the active metal, is present down to a penetration depth ofnot more than 200 μm, i.e. in a shell with a distance of not more than200 μm from the surface of the catalyst particles. In contrast, only avery small amount, if any, of the active metal is present in theinterior (core) of the catalyst. Very particular preference is given toan inventive shell catalyst in which no active metal can be detected inthe interior of the catalyst, i.e. active metal is present only in theoutermost shell, for example in a zone down to a penetration depth of100 to 200 μm. The aforementioned data can be determined by means of SEM(scanning electron microscopy), EPMA (electron probe microanalysis)-EDXS(energy dispersive X-ray spectroscopy), and are averaged values. Furtherdata with regard to the aforementioned test methods and techniques canbe found, for example, in “Spectroscopy in Catalysis” by J. W.Niemantsverdriet, VCH, 1995. For further details regarding thepenetration depth of active metal, reference is made to WO 2006/136541,especially to page 7 lines 6 to 12.

Preferred shell catalysts have a content of active metal in the rangefrom 0.05 to 1% by weight, especially 0.1 to 0.5% by weight, morepreferably 0.25 to 0.35% by weight, based in each case on the totalweight of the catalyst.

For the inventive hydrogenation in step b), particular preference isgiven to shell catalysts with a support material based on silicondioxide, generally amorphous silicon dioxide. The term “amorphous” inthis context is understood to mean that the proportion of crystallinesilicon dioxide phases makes up less than 10% by weight of the supportmaterial. The support materials used to prepare the catalysts may,however, have superstructures which are formed via regular arrangementof pores in the support material. Useful support materials are inprinciple amorphous silicon dioxide types which consist at least to anextent of 90% by weight of silicon dioxide, where the remaining 10% byweight, preferably not more than 5% by weight, of the support materialmay also be another oxidic material, for example MgO, CaO, TiO₂, ZrO₂,Fe₂O₃ and/or alkali metal oxide. In a preferred embodiment of the shellcatalyst, the support material is halogen-free, especiallychlorine-free, i.e. the content of halogen in the support material isless than 500 ppm by weight, for example in the range from 0 to 400 ppmby weight. Thus, a preferred shell catalyst is one which comprises lessthan 0.05% by weight of halide (determined by ion chromatography), basedon the total weight of the catalyst. Preference is given to supportmaterials which have a specific surface area in the range from 30 to 700m²/g, preferably 30 to 450 m²/g (BET surface area to DIN 66131).Suitable amorphous support materials based on silicon dioxide arefamiliar to those skilled in the art and are commercially available(see, for example, O. W. Flörke, “Silica” in Ullmann's Encyclopedia ofIndustrial Chemistry, 6th Edition on CD-ROM). They may either be ofnatural origin or may have been produced synthetically. Examples ofsuitable amorphous support materials based on silicon dioxide are silicagels, kieselguhr, fumed silicas and precipitated silicas. In a preferredembodiment of the invention, the catalysts have silica gels as supportmaterials. According to the configuration of the shell catalyst, thesupport material may have different shapes. When the process in whichthe inventive shell catalysts are used is configured as a suspensionprocess, the inventive catalysts will typically be prepared using thesupport material in the form of a fine powder. The powder preferably hasparticle sizes in the range from 1 to 200 μm, especially 1 to 100 μm. Inthe case of use of the inventive shell catalyst in fixed catalyst beds,it is customary to use shaped bodies of the support material, which areobtainable, for example, by extrusion or tableting, and which may have,for example, the form of spheres, tablets, cylinders, extrudates, ringsor hollow cylinders, stars and the like. The dimensions of these shapedbodies typically vary within the range from 0.5 mm to 25 mm. Frequently,catalyst extrudates with extrudate diameters of 1.0 to 5 mm andextrudate lengths of 2 to 25 mm are used. It is generally possible toachieve higher activities with smaller extrudates; these, however, oftendo not have sufficient mechanical stability in the hydrogenationprocess. Therefore, very particular preference is given to usingextrudates with extrudate diameters in the range from 1.5 to 3 mm.Preference is likewise given to spherical support materials with spherediameters in the range from 1 to 10 mm, especially 2 to 6 mm.

In a particularly preferred embodiment of the shell catalysts, thesupport material of the catalyst, which is especially a support materialbased on silicon dioxide, has a pore volume in the range from 0.6 to 1.0ml/g, preferably in the range from 0.65 to 0.9 ml/g, for example 0.7 to0.8 ml/g, determined by Hg porosimetry (DIN 66133), and a BET surfacearea in the range from 280 to 500 m²/g, preferably in the range from 280to 400 m²/g, most preferably in the range from 300 to 350 m²/g. In suchshell catalysts, at least 90% of the pores present preferably have adiameter of 6 to 12 nm, preferably 7 to 11 nm, more preferably 8 to 10nm. The pore diameter can be determined by processes known to thoseskilled in the art, for example by Hg porosimetry or N₂ physisorption.In a preferred embodiment, at least 95%, more preferably at least 98%,of the pores present have a pore diameter of 6 to 12 nm, preferably 7 to11 nm, more preferably 8 to 10 nm. In a preferred embodiment, no poressmaller than 5 nm are present in these shell catalysts. Furthermore,there are preferably no pores larger than 25 nm, especially larger than15 nm, in these shell catalysts. In this composition, “no pores” meansthat no pores with these diameters can be found by customary testmethods, for example Hg porosimetry or N₂ physisorption.

In preferred shell catalysts, the dispersity of the active metal ispreferably 30 to 60%, more preferably 30 to 50%. Processes for measuringthe dispersity of the active metal are known per se to those skilled inthe art, for example by pulse chemisorption, the determination of thenoble metal dispersion (specific metal surface area, crystal size) beingcarried out by the CO pulse method (DIN 66136(1-3)).

The hydrogenation process according to the invention can be performed inthe liquid phase or in the gas phase. Preference is given to performingthe hydrogenation process according to the invention in the liquidphase.

The hydrogenation process according to the invention can be performed inthe absence of a solvent or diluent or in the presence of a solvent ordiluent, i.e. it is not necessary to perform the hydrogenation insolution. The solvent or diluent used may be any suitable solvent ordiluent. Useful solvents or diluents are in principle those which arecapable of very substantially dissolving the organic compounds to behydrogenated, or mix completely therewith, and which are inert under thehydrogenation conditions, i.e. are not hydrogenated. Examples ofsuitable solvents are cyclic and acyclic ethers having preferably 4 to 8carbon atoms, for example tetrahydrofuran, dioxane, methyl tert-butylether, dimethoxyethane, dimethoxypropane, dimethyldiethylene glycol,aliphatic alcohols having preferably 1 to 6 carbon atoms, such asmethanol, ethanol, n- or isopropanol, n-, 2-, iso- or tert-butanol,carboxylic esters of aliphatic carboxylic acids having preferably 3 to 8carbon atoms, such as methyl acetate, ethyl acetate, propyl acetate orbutyl acetate, methyl propionate, ethyl propionate, butyl propionate,and aliphatic ether alcohols such as methoxypropanol, and cycloaliphaticcompounds such as cyclohexane, methylcyclohexane anddimethylcyclohexane. The amount of the solvent or diluent used is notparticularly restricted and can be selected freely as required,although, when using a solvent, preference is given to those amountswhich lead to a 3 to 70% by weight solution of the organic compoundintended for hydrogenation.

In one embodiment of the invention, step b) of the invention isperformed in substance.

The actual hydrogenation is effected typically in analogy to the knownhydrogenation processes for hydrogenating organic compounds which havehydrogenatable groups, preferably for hydrogenating a carbocyclicaromatic group to the corresponding carbocyclic aliphatic group, asdescribed in the prior art cited at the outset. For this purpose, theorganic compound as a liquid phase or gas phase, preferably as a liquidphase, is contacted with the catalyst in the presence of hydrogen. Theliquid phase can be passed over a moving catalyst bed (moving bed mode)or a fixed catalyst bed (fixed bed mode).

The hydrogenation can be configured either continuously or batchwise,preference being given to the continuous process regime. The processaccording to the invention is preferably performed in trickle reactorsor in flooded mode by the fixed bed mode, particular preference beinggiven to performance in trickle reactors. More particularly, thecompound to be hydrogenated here is used in substance, i.e. substantialabsence of organic diluents (solvent content preferably <10%). Thehydrogenation can be passed over the catalyst either in cocurrent withthe solution of the reactant to be hydrogenated or in countercurrent.The hydrogenation can also be performed batchwise in batchwise mode. Inthis case, the hydrogenation will preferably be performed in an organicsolvent or diluent.

In the case of batchwise performance of the process according to theinvention, in step B, the catalyst is typically used in an amount suchthat the concentration of ruthenium in the reaction mixture used forhydrogenation is in the range from 10 to 10 000 ppm, especially in therange from 50 to 5000 ppm, especially in the range from 100 to 1000 ppm.

The hydrogenation is effected typically at a hydrogen pressure in therange from 5 to 50 MPa, especially in the range from 10 to 30 MPa. Thehydrogen can be fed into the reactor as such, or diluted with an inert,for example nitrogen or argon.

The hydrogenation in step b) is effected typically at temperatures above50° C., especially in the range from 100 to 250° C.

Apparatus suitable for performing the hydrogenation is known to thoseskilled in the art and is guided primarily by the mode of operation.Suitable apparatus for performing a hydrogenation according to thehydrogenation over a moving catalyst bed and over a fixed catalyst bedare known, for example, from Ullmanns Enzyklopädie der TechnischenChemie, 4th edition, volume 13, p. 135 ff., and from P. N. Rylander,“Hydrogenation and Dehydrogenation” in Ullmann's Encyclopedia ofIndustrial Chemistry, 5th ed. on CD-ROM.

It has been found that, surprisingly, step a) of the process accordingto the invention affords not only 2-methyl-4-phenyl-2-butanol but also asmall amount of 2-methyl-4-phenyl-2-pentanol when it is performed underconditions under which isopropanol is present under supercriticalconditions, especially when the molar ratio of styrene to isopropanol isin the range from 1:10 to 1:130, particularly in the range from 1:30 to1:120, more preferably in the range from 1:40 to 1:100 and especially inthe range from 1:50 to 1:90, and/or when the reaction is performed insemibatchwise mode.

Such a process is novel and likewise forms part of the subject matter ofthe present invention. Accordingly, the invention relates to a processfor preparing a composition comprising 2-methyl-4-phenyl-2-butanol and2-methyl-4-phenyl-2-pentanol, comprising the reaction of styrene withisopropanol at elevated temperature under conditions under whichisopropanol is present under supercritical conditions, the molar ratioof styrene to isopropanol being in the range from 1:10 to 1:130particularly in the range from 1:30 to 1:120, more preferably in therange from 1:40 to 1:100 and especially in the range from 1:50 to 1:90.

It has been found to be advantageous when the reaction is performed insemibatchwise mode or continuously, as already described above for stepa). For this purpose, it has been found to be especially advantageouswhen at least 80%, especially at least 90%, of the isopropanol used isinitially charged, optionally together with a portion of the styrene,and at least 80%, especially at least 90%, of the styrene used issupplied to the reaction under reaction conditions. The styrene can beadded in portions or preferably continuously. The rate with which thestyrene is supplied is preferably selected such that the molar ratio ofthe styrene fed into the reaction zone or the reactor to the isopropanolpresent in the reaction zone is in the range from 1:10 to 1:130,particularly in the range from 1:20 to 1:120, more preferably in therange from 1:40 to 1:100 and especially in the range from 1:50 to 1:90.This is especially true, in a continuous reaction regime too, of themolar ratios of styrene and isopropanol supplied to the reactor or tothe reaction zone.

Otherwise, the conditions specified above for step a) also apply in thesame way to the process according to the invention for preparing acomposition comprising 2-methyl-4-phenyl-2-butanol and2-methyl-4-phenyl-2-pentanol. Reference is therefore made to thesedetails in full.

Such a process affords compositions which comprise2-methyl-4-phenyl-2-butanol and 2-methyl-4-phenyl-2-pentanol. The weightratio of 2-methyl-4-phenyl-2-butanol to 2-methyl-4-phenyl-2-pentanol insuch compositions is typically in the range from 50:1 to 1000:1.

The reaction mixture obtained in the preparation of a compositioncomprising 2-methyl-4-phenyl-2-butanol and 2-methyl-4-phenyl-2-pentanolby reaction of styrene with isopropanol can be worked up in the mannerdescribed above for step a). Reference is made completely to the detailsgiven above for workup of the reaction mixture obtained in step a). Moreparticularly, the reaction mixture obtained is worked up bydistillation, in which case the desired composition consistingessentially of 2-methyl-4-phenyl-2-butanol and2-methyl-4-phenyl-2-pentanol is removed as the middle fraction from lowand high boilers. In general, a composition is then obtained whichconsists essentially, i.e. to an extent of at least 95% by weight,particularly at least 98% by weight and especially at least 99% byweight or at least 99.5% by weight of 2-methyl-4-phenyl-2-butanol, andsmall amounts of 2-methyl-4-phenyl-2-pentanol, for example compositionsin which the weight ratio of 2-methyl-4-phenyl-2-butanol to2-methyl-4-phenyl-2-pentanol in the range from 50:1 to 1000:1.

Such mixtures of 2-methyl-4-phenyl-2-butanol and small amounts of2-methyl-4-phenyl-2-pentanol can subsequently be hydrogenated in analogyto step b) to obtain compositions comprising4-cyclohexyl-2-methyl-2-butanol and small amounts of4-cyclohexyl-2-methyl-2-pentanol, for example compositions in which theweight ratio of 4-cyclohexyl-2-methyl-2-butanol to4-cyclohexyl-2-methyl-2-pentanol is in the range from 50:1 to 1000:1.Reference is made completely to the details given above for thehydrogenation in step b). Since an isopropanol excess can be employed inthe preparation of a composition comprising 2-methyl-4-phenyl-2-butanoland 2-methyl-4-phenyl-2-pentanol, the low boiler fraction, whichconsists predominantly of isopropanol, can be recycled into the process.In general, isopropanol will be substantially removed before thehydrogenation, such that the proportion of isopropanol in the reactantused for the hydrogenation is less than 20% by weight, especially notmore than 10% by weight, based on the total amount of reactant.

Compositions comprising 2-methyl-4-phenyl-2-butanol and2-methyl-4-phenyl-2-pentanol are surprisingly notable in that they havea more flowery odor note compared to 2-methyl-4-phenyl-2-butanol. Suchcompositions are novel and likewise form part of the subject matter ofthe invention. In these compositions, the weight ratio of2-methyl-4-phenyl-2-butanol to 2-methyl-4-phenyl-2-pentanol is in therange from 50:1 to 1000:1. A specific composition is that ofconcentrates, i.e. compositions which consist essentially, i.e. to anextent of at least 95% by weight, particularly at least 98% by weightand especially at least 99% by weight or at least 99.5% by weight of2-methyl-4-phenyl-2-butanol and small amounts of2-methyl-4-phenyl-2-pentanol, for example compositions in which theweight ratio of 2-methyl-4-phenyl-2-butanol to2-methyl-4-phenyl-2-pentanol is in the range from 50:1 to 1000:1.Compositions in which the weight ratio of 2-methyl-4-phenyl-2-butanol to2-methyl-4-phenyl-2-pentanol is outside the range specified here can beprepared by mixing 2-methyl-4-phenyl-2-butanol (Muguet alcohol) with thedesired amount of 2-methyl-4-phenyl-2-pentanol. Such compositions ofcourse likewise form part of the subject matter of the presentinvention.

Such compositions, especially the aforementioned concentrates, can beused as fragrances or aromas for the reasons mentioned above, especiallyin cosmetic compositions and in washing or cleaning compositions.

The invention therefore also provides cosmetic compositions whichcomprise a composition comprising 2-methyl-4-phenyl-2-butanol and2-methyl-4-phenyl-2-pentanol.

The invention therefore also provides washing or cleaning compositionswhich comprise a composition comprising 2-methyl-4-phenyl-2-butanol and2-methyl-4-phenyl-2-pentanol.

It has additionally been found in the context of this invention that2-methyl-4-phenyl-2-pentanol can also be prepared in a controlled mannerby reacting α-methylstyrene with isopropanol under the conditionsspecified above for step a).

The invention therefore also provides a process for preparing2-methyl-4-phenyl-2-pentanol, in which α-methylstyrene is reacted withisopropanol at elevated temperature. For the reaction of α-methylstyrenewith isopropanol, essentially all details apply which have been givenabove and in the claims for the reaction of styrene with isopropanol instep a). Reference is therefore made completely to these details.

Alternatively, 2-methyl-4-phenyl-2-pentanol or a mixture consistingessentially of 2-methyl-4-phenyl-2-pentanol can be obtained bydistillative separation of mixtures comprising2-methyl-4-phenyl-2-butanol and 2-methyl-4-phenyl-2-pentanol, forexample by distillative separation of mixtures as obtained in step a) ofthe process according to the invention.

2-Methyl-4-phenyl-2-pentanol is likewise an odorant and can therefore beused in all applications for odorants of this type. As already statedabove, it can surprisingly also be used for modification of the odorproperties of 2-methyl-4-phenyl-2-butanol. The use of2-methyl-4-phenyl-2-pentanol as an odorant has not been described todate. It therefore likewise forms part of the subject matter of thepresent invention, more particularly the use of2-methyl-4-phenyl-2-pentanol as an odorant in cosmetic compositions andin washing or cleaning compositions.

The invention therefore also provides cosmetic compositions comprising2-methyl-4-phenyl-2-pentanol.

The invention therefore also provides washing or cleaning compositionscomprising 2-methyl-4-phenyl-2-pentanol.

2-Methyl-4-phenyl-2-pentanol can be subjected to a hydrogenation inanalogy to step b). This gives 4-cyclohexyl-2-methyl-2-pentanol in ahigh yield.

4-Cyclohexyl-2-methyl-2-pentanol is novel and likewise forms part of thesubject matter of the present invention.

4-Cyclohexyl-2-methyl pentanol is, similarly to4-cyclohexyl-2-methyl-2-butanol, an odorant. In addition, it cansurprisingly be used for modification of the odor properties of otherodorants, especially of 4-cyclohexyl-2-methyl-2-butanol.4-Cyclohexyl-2-methyl-2-pentanol can therefore be used as a fragrance oraroma, especially in cosmetic compositions and in washing or cleaningcompositions.

The invention therefore also provides cosmetic compositions comprising4-cyclohexyl-2-methyl-2-pentanol.

The invention therefore also provides washing or cleaning compositionscomprising 4-cyclohexyl-2-methyl-2-pentanol.

Compositions which comprise 4-cyclohexyl-2-methyl-2-butanol and4-cyclohexyl-2-methyl-2-pentanol are surprisingly notable in that,compared with 4-cyclohexyl-2-methyl-2-butanol, they have a more floweryodor note. Such compositions are novel and likewise form part of thesubject matter of the invention.

In these compositions, the weight ratio of4-cyclohexyl-2-methyl-2-butanol to 4-cyclohexyl-2-methyl-2-pentanol isgenerally in the range from 50:1 to 1000:1. Such compositions may alsocomprise small amounts of 4-cyclohexyl-2-methylbutane and possibly4-cyclohexyl-2-methylpentane, which are obtained by over-reduction of2-methyl-4-phenyl-2-butanol and 2-methyl-4-phenyl-2-pentanolrespectively. The proportion by weight of the total amount ofcyclohexyl-2-methylbutane and any 4-cyclohexyl-2-methylpentane willgenerally not exceed 10% by weight, especially 5% by weight, based on4-cyclohexyl-2-methyl-2-butanol, and is, if present, in the range from0.01 to 10% by weight, especially in the range from 0.01 to 5% byweight, based on 4-cyclohexyl-2-methyl-2-butanol. It is of course alsopossible to remove cyclohexyl-2-methylbutane and any4-cyclohexyl-2-methylpentane, for example by a distillative route, suchthat the total amount of cyclohexyl-2-methylbutane and any4-cyclohexyl-2-methylpentane is less than 1% by weight, especially lessthan 0.5% by weight or less than 0.1% by weight, based on4-cyclohexyl-2-methyl-2-butanol. A specific composition is that ofconcentrates, i.e. compositions which consist essentially, i.e. to anextent of at least 95% by weight, particularly at least 98% by weightand especially at least 99% by weight or at least 99.5% by weight of4-cyclohexyl-2-methyl-2-butanol and small amounts of4-cyclohexyl-2-methyl-2-pentanol, for example compositions in which theweight ratio of 4-cyclohexyl-2-methyl-2-butanol to4-cyclohexyl-2-methyl-2-pentanol is in the range from 50:1 to 1000:1.

These concentrates may comprise cyclohexyl-2-methylbutane and possibly4-cyclohexyl-2-methylpentane in the amounts mentioned above.Compositions in which the weight ratio of4-cyclohexyl-2-methyl-2-butanol to 4-cyclohexyl-2-methyl-2-pentanol isoutside the range specified here can be prepared by mixingcyclohexyl-2-methyl-2-butanol with the desired amount of4-cyclohexyl-2-methyl-2-pentanol. Such compositions of course likewiseform part of the subject matter of the present invention.

Such compositions, especially the aforementioned concentrates, can beused as fragrances or aromas for the reasons mentioned above, especiallyin cosmetic compositions and in washing or cleaning compositions.

The invention therefore also provides cosmetic compositions whichcomprise a composition comprising 4-cyclohexyl-2-methyl-2-butanol and4-cyclohexyl-2-methyl-2-pentanol.

The invention therefore also provides washing or cleaning compositionswhich comprise a composition comprising 4-cyclohexyl-2-methyl-2-butanoland 4-cyclohexyl-2-methyl-2-pentanol.

As already stated above, 4-cyclohexyl-2-methyl-2-pentanol can beprepared from 2-methyl-4-phenyl-2-pentanol in analogy to step b), i.e.by a process comprising a heterogeneously catalyzed hydrogenation of2-methyl-4-phenyl-2-pentanol over a catalyst suitable for ringhydrogenation of aromatics. Such a process likewise forms part of thesubject matter of the present invention. With regard to thehydrogenation of 2-methyl-4-phenyl-2-pentanol, reference is madecompletely to the details given above for the hydrogenation in step b).

The procedure here may be first to prepare 2-methyl-4-phenyl-2-pentanolin a controlled manner and then to subject it to a heterogeneouslycatalyzed hydrogenation over a catalyst suitable for ring hydrogenationof aromatics, in analogy to step b) described above.

However, the procedure may also be first to prepare a compositioncomposed of 2-methyl-4-phenyl-2-butanol and2-methyl-4-phenyl-2-pentanol, for example in the manner described abovefor step a), to subject this composition to a heterogeneously catalyzedhydrogenation over a catalyst suitable for ring hydrogenation ofaromatics in analogy to the above-described step b), and to separate thecomposition obtained, which comprises 4-cyclohexyl-2-methyl-2-butanoland 4-cyclohexyl-2-methyl-2-pentanol, into its constituents bydistillation.

Accordingly, the invention also relates to a process for preparing4-cyclohexyl-2-methyl-2-pentanol, comprising the following steps:

-   a′) preparation of a composition comprising    2-methyl-4-phenyl-2-butanol and 2-methyl-4-phenyl-2-pentanol by    reaction of styrene with isopropanol at elevated temperature under    conditions under which isopropanol is present under supercritical    conditions, the molar ratio of styrene to isopropanol being in the    range from 1:10 to 1:130;-   b′) heterogeneously catalyzed hydrogenation of the composition    obtained in step a) over a catalyst suitable for ring hydrogenation    of aromatics; and-   c) distillative workup of the composition obtained in step b′) to    obtain a composition consisting essentially, i.e. to an extent of at    least 90% by weight, especially to an extent of at least 95% by    weight, of 4-cyclohexyl-2-methyl-2-pentanol.

Accordingly, the invention further relates to a process for preparing4-cyclohexyl-2-methyl-2-pentanol, comprising the following steps:

-   a′) preparation of a composition comprising    2-methyl-4-phenyl-2-butanol and 2-methyl-4-phenyl-2-pentanol by    reaction of styrene with isopropanol at elevated temperature under    conditions under which isopropanol is present under supercritical    conditions, the molar ratio of styrene to isopropanol being in the    range from 1:10 to 1:130;-   c′) distillative workup of the composition obtained in step a′) to    obtain a composition consisting predominantly of    2-methyl-4-phenyl-2-pentanol-   b′) heterogeneously catalyzed hydrogenation of the composition    obtained in step c′) over a catalyst suitable for ring hydrogenation    of aromatics; and optionally-   c″) distillative workup of the composition obtained in step b′) to    obtain a composition consisting essentially of    4-cyclohexyl-2-methyl-2-pentanol.

It will be appreciated that step a′) is performed in analogy to the stepa) already described above. To that extent, for step a′), reference ismade completely to the details given for step a).

It will also be appreciated that step b′) is performed in analogy to thestep ab) already described above. To that extent, for step b′),reference is made completely to the remarks made for step b).

The distillative steps c), c′) and c″) can be performed in analogy tocustomary processes for fractional distillation. Suitable apparatus forthis purpose is familiar to those skilled in the art. The necessaryconditions can be determined by routine experiments. In general,distillation is effected under reduced pressure.

In addition, the invention additionally relates to a process forpreparing 4-cyclohexyl-2-methyl-2-pentanol, comprising the followingsteps:

-   a″) reaction of α-methylstyrene with isopropanol at elevated    temperature to obtain 2-methyl-4-phenyl-2-pentanol, and-   b″) heterogeneously catalyzed hydrogenation of    2-methyl-4-phenyl-2-pentanol over a catalyst suitable for ring    hydrogenation of aromatics.

As already explained above, step a″) is performed in analogy to the stepa) already described above. To that extent, for step a″), reference ismade completely to the details given for step a).

It will also be appreciated that step b″) is performed in analogy to thestep ab) already described above. To that extent, for step b″),reference is made completely to the details given for step b).

It will also be appreciated that the reaction product obtainable in stepa″), before use thereof in step b″), can be subjected to a workup inanalogy to that for the reaction product obtained in step a) above,especially to a distillative workup in which low boilers and highboilers are removed, and 2-methyl-4-phenyl-2-pentanol is obtained as amedium boiler. In this regard, reference is likewise made to the detailsgiven above.

As already stated above, the invention also relates to cosmeticcompositions which comprise one of the following substances or substancemixtures as fragrances or aromas:

-   i. 4-cyclohexyl-2-methyl-2-pentanol;-   ii. 2-methyl-4-phenyl-2-pentanol;-   iii. composition comprising 2-methyl-4-phenyl-2-butanol and    2-methyl-4-phenyl-2-pentanol; or-   iv. composition comprising 4-cyclohexyl-2-methyl-2-butanol and    4-cyclohexyl-2-methyl-2-pentanol.

Examples of suitable cosmetic compositions are in principle all cosmeticcompositions which typically comprise fragrances. These include, forexample, eau de partum, eau de toilette, eau de cologne, aftershaveproducts such as lotions and creams, preshave products, perfumed wetwipes, hair removal creams and lotions, tanning creams and lotions,haircare products such as shampoos, hair rinses, hairsetting products,hair gels, hair tints, hair waxes, hair sprays, setting foams, hairmousses, split end fluids, neutralizing agents for permanent waves, hairdyes and bleaches or hot oil treatments, and also skin cleansingproducts such as soaps, washing gels, shower gels, bodycare productssuch as creams, oils, lotions and the like for skin, especially productsfor care of the hands, of the face and of the feet, sunscreens,deodorants and antiperspirants, skin disinfectants, insect repellentsand decorative cosmetic products. According to the field of use, thecosmetic compositions may be formulated as aqueous or alcoholic liquid,oil, (aerosol) spray, (aerosol) foam, mousse, gel, gel spray, cream,lotion, powder, tabs or wax.

As already stated above, the invention also relates to washing orcleaning compositions which comprise one of the following substances orsubstance mixtures as fragrances or aromas:

-   i. 4-cyclohexyl-2-methyl-2-pentanol;-   ii. 2-methyl-4-phenyl-2-pentanol;-   iii. composition comprising 2-methyl-4-phenyl-2-butanol and    2-methyl-4-phenyl-2-pehtanol; or-   iv. composition comprising 4-cyclohexyl-2-methyl-2-butanol and    4-cyclohexyl-2-methyl-2-pentanol.

These include products for cleaning and/or disinfection of surfaces, forexample household cleaners, neutral cleaners, toilet cleaners, floorcleaners, carpet cleaners, window cleaners, polishes, furniture careproducts, liquid and solid dishwashing products, liquid and solidmachine dishwashing products, and also products for cleaning ortreatment of textiles, such as solid or liquid textile washingcompositions, laundry aftertreatment compositions, fabric softeners,ironing aids, textile fresheners, fabric preconditioners, washing soaps,washing tablets and the like.

In addition, the inventive substances and substance mixtures can be usedas a fragrance constituent in other fragrance-containing products, suchas air conditioners, lamp oils, candles, air fresheners and the like.

The invention is illustrated in detail by the examples which follow:

Preparation Example 1 Preparation of the Hydrogenation Catalyst

The support material used was a spherical SiO₂ support (AF125 type fromBASF SE) with a sphere diameter of 3 to 5 mm and a tapped density of0.49 kg/l. The BET surface area was 337 m²/g, and the water absorption(WA) 0.83 ml/g. For impregnation, 14.25% by weight ruthenium(III)acetate solution in acetic acid from Umicore was used.

200 g of support were initially charged in a round-bottom flask. 15 g ofruthenium acetate solution were diluted with distilled water to 150 ml(90% WA). The support material was initially charged in the distillationflask of a rotary evaporator, and the first quarter of the solution waspumped onto the support material at 3 to 6 rpm with a slightly reducedpressure. On completion of the addition, the support was left in therotary evaporator at 3 to 6 rpm for a further 10 minutes, in order tohomogenize the catalyst. This impregnation-homogenization step wasrepeated three times more until all of the solution had been applied tothe support. The support material thus treated was dried while beingagitated in the rotary tube oven at 140° C., then reduced in a hydrogenstream (20 l/h of H₂; 10 l/h of N₂) at 200° C. for 3 h, and passivatedat 25° C. (5% air in N₂, 2 h). The inventive catalyst A thus obtainedcomprised 0.34% by weight of ruthenium, based on the catalyst weight.

Step a) Example 1

A 400 ml autoclave was initially charged with 2.08 g (20.0 mmol) ofstyrene and 51.2 g (853 mmol) of isopropanol. The autoclave was closedand the reaction mixture was stirred at 350° C. (autogenous pressure 230bar). After a reaction time of 2 h in each case, another 2.08 g (20.0mmol) of styrene were added. After a total of 14 additions,corresponding to a total amount of styrene of 31.2 g (300 mmol), thereaction mixture was allowed to cool, and the autoclave wasdecompressed. Before each addition, a sample was taken and analyzed bymeans of gas chromatography for the composition thereof. In this way,the selectivity of the formation of 2-methyl-4-phenyl-2-butanol wasdetermined based on the styrene used. The selectivities are reported inthe table which follows:

Styrene [mmol] 40 80 120 160 200 240 280 300 Reaction time[h] 4 8 12 1620 24 28 30 Selectivity [%] 90.0 81.8 77.3 70.9 67.9 63.9 59.6 57.3

The reaction mixture was worked up by distillation. After removing thelow boilers (in particular isopropanol), a crude product of purity >75%was obtained, which also comprised 2-methyl-4-phenyl-2-pentanol (1.0 GCarea %). Further fine distillation gave 25.7 g (0.151 mol) of4-phenyl-2-methylbutan-2-ol, corresponding to a yield of 50.3%.

A mixture of 2-methyl-4-phenyl-2-butanol (99.8%) and2-methyl-4-phenyl-2-pentanol (0.11 GC area %) obtained in the finedistillation was notable, in terms of odor, especially for an additionalpleasant, faintly flowery note compared to the pure substance2-methyl-4-phenyl-2-butanol.

Example 2

A 400 ml autoclave was additionally charged with 118 g (1.96 mol) ofisopropanol. The autoclave was closed and brought to internaltemperature 375° C. (autogenous pressure 244 bar). 2.06 g (19.8 mmol) ofstyrene were added rapidly thereto and, after 15 min of reaction time,another 2.08 g (20.0 mmol) of styrene were added thereto. Styrene wasadded in this way four more times. After a total of 6 additions,corresponding to a total amount of styrene of 12.36 g (119 mmol), thereaction mixture was allowed to cool and then the autoclave wasdecompressed. Before each addition, a sample was taken and analyzed bymeans of gas chromatography for the composition thereof. In this way,the selectivity of the formation of 2-methyl-4-phenyl-2-butanol based onthe styrene used was determined. The selectivities are reported in thefollowing table:

Styrene [mmol] 19.8 38.6 59.4 79.2 99 118.8 Reaction time [min] 15 30 4560 75 90 Selectivity [%] 72.1 62.5 65.5 65.1 65.2 63.6

Example 3 Continuous Mode

A 300 ml autoclave was initially charged with 78 g of isopropanol. Theautoclave was closed and the reaction mixture was heated to internaltemperature 350° C. (autogenous pressure 150 bar). Subsequently,continuous dosage and withdrawal were effected under pressure control,such that pressure and temperature always remained constant. A mixtureof styrene and isopropanol in a ratio of 1:10 (parts by weight) wasmetered in at a flow rate of 40 g/h. Correspondingly, an output of 40g/h was withdrawn from the reactor.

The course of the reaction was monitored by means of gas chromatography.A steady state was established in the reactor after approx. 10 h. Thestyrene conversion was determined to be 75%, and an output of2-methyl-4-phenyl-2-butanol of 2 g/h was found.

Example 4

A 400 ml autoclave was initially charged with 51.2 g (853 mmol) ofisopropanol. The autoclave was closed and the contents were stirred at350° C. (autogenous pressure 230 bar). A metering pump was used to addstyrene to the autoclave at an addition rate of 1.04 g/h (10 mmol/h)over a period totaling 20 h. Subsequently, the reaction mixture wasallowed to cool and the autoclave was decompressed. Samples were takenat intervals of 4 h and analyzed by means of gas chromatography for thecomposition thereof. In this way, the selectivity of the formation of2-methyl-4-phenyl-2-butanol based on the styrene used was determined.The selectivities are reported in the table which follows:

Styrene [mmol] 40 80 120 160 200 Reaction time [h] 4 8 12 16 20 Pressure[MPa] 20.3 20.7 20.1 18.4 18.4 Selectivity [%] 81.8 71.3 65.1 62.2 58.0

Step b) Example 5

A 300 ml autoclave was initially charged with 10.2 g of2-methyl-4-phenyl-2-butanol (62 mmol), dissolved in 150 ml oftetrahydrofuran, and 1.7 g of the catalyst from preparation example 1 ina catalyst basket. The autoclave was purged three times with nitrogen,acid then hydrogen was injected to pressure 200 bar at 200° C. for 12hours. After 6 and 12 hours, the progress of the reaction was analyzedby means of gas chromatography (30 m, column material DB1, internaldiameter: 0.25 mm, film thickness: 0.25 μm, temperature program 50° C.—5min isothermal; 6° C./min.→290° C.—219 min. isothermal). The productcontents are reported in the table which follows.

4-Cyclohexyl- 2-Methyl-4-phenyl- 4-Cyclohexyl- 2-methyl-2-butanol2-butanol 2-methylbutane  6 hours 88.9% 0% 5.9% 12 hours 88.2% 0% 6.8%

After only 6 h, no starting material was detectable any longer. The lowproportion of by-products such as 4-cyclohexyl-2-methylbutanedemonstrates the high selectivity of the hydrogenation for the desiredtarget compound 4-cyclohexyl-2-methyl-2-butanol.

Example 6

In a 300 mL autoclave, 70 g of 2-methyl-4-phenyl-2-butanol (0.43 mol)were dissolved in 97 g of tetrahydrofuran, and 2.2 g of a catalystaccording to preparation example 1 were initially charged in a catalystbasket. The autoclave was purged three times with nitrogen. This wasfollowed by hydrogenation at 160° C. and hydrogen pressure 160 bar for10 hours. The output was analyzed by means of gas chromatography (30 mcolumn material DB1 ID: 0.25 mm, FD: 0.25 μm, 50° C.—5 min isothermal,−6° C./min→290° C.—219 min isothermal). The composition of the outputafter 10 h is reported in the table below.

4-Cyclohexyl- 2-Methyl-4-phenyl- 4-Cyclohexyl- 2-methyl-2-butanol2-butanol 2-methylbutane Comp. 10 h 95.4% 0.0% 4.6% [area %]¹⁾¹⁾Composition of the output after 10 h

Example 7

A 300 mL autoclave was initially charged with 160 g of2-methyl-4-phenyl-2-butanol (0.98 mol) and 6.4 g of a catalyst accordingto example 1 of EP 1042273 (0.5% Ru/Al₂O₃) in a catalyst basket. Theautoclave was purged with nitrogen three times. This was followed byhydrogenation at 160° C. and hydrogen pressure 160 bar for 10 hours. Theoutput was analyzed by means of gas chromatography (30 m column materialDB1 ID: 0.25 mm, FD: 0.25 μm, 50° C.—5 min isothermal, −6° C./min→290°C.—219 min isothermal). The composition of the output after 10 h isreported in the table below.

4-Cyclohexyl- 2-Methyl-4- 4-Cyclohexyl- 2-methyl-2-butanolphenyl-2-butanol 2-methylbutane Comp. 10 h 90.1% 0.1% 2.5% [area %]¹⁾¹⁾Composition of the output after 10 h

Example 8

A 300 mL autoclave was initially charged with 160 g of2-methyl-4-phenyl-2-butanol (0.98 mol) and 0.64 g of a commerciallyavailable supported Rh catalyst (Escat 34, from Engelhard-5% Rh/Al₂O₃)in a catalyst basket. The autoclave was purged three times withnitrogen, and this was followed by hydrogenation at 160° C. and hydrogenpressure 160 bar for 10 hours. The output was analyzed by means of gaschromatography (30 m column material DB1 ID: 0.25 mm, FD: 0.25 μm, 50°C.—5 min isothermal, −6° C./min→290° C.—219 min isothermal). Thecomposition of the output after 10 h is reported in the table below.

4-Cyclohexyl- 2-Methyl-4- 4-Cyclohexyl- 2-methyl-2-butanolphenyl-2-butanol 2-methylbutane Comp. 10 h 92.5% 0.0% 0.25% [area %]¹⁾¹⁾Composition of the output after 10 h

Example 9

A 300 mL autoclave was initially charged with 160 g of2-methyl-4-phenyl-2-butanol (0.98 mol) and 0.04 g of a commercial nickelcatalyst (Ni5249P, from BASF, approx. 65% Ni/SiO₂/MgO). The autoclavewas purged three times with nitrogen, and this was followed byhydrogenation at 160° C. and hydrogen pressure 160 bar for 10 hours. Theoutput was analyzed by means of gas chromatography (30 m column materialDB1 ID: 0.25 mm, FD: 0.25 μm, 50° C.—5 min isothermal, −6° C./min→290°C.—219 min isothermal). The composition of the output after 10 h isreported in the table below.

4-Cyclohexyl- 2-Methyl-4-phenyl- 4-Cyclohexyl- 2-methyl-2-butanol2-butanol 2-methylbutane Comp. 10 h 86.9% 4.6% 1.02% [area %]¹⁾¹⁾Composition of the output after 10 h

Example 10

The reaction was conducted in a continuous laboratory plant whichcomprises a main reactor composed of three series-connected tubularreactors with circulation (main reactor (MR)) and a postreactor (PR)configured as a tubular reactor. The tubular reactors were filled withthe catalyst A prepared according to preparation example 1 as follows:MR: each tube 7.7 g, PR: 3.25 g. The first and third tubes of the mainreactor were operated in trickle mode, the second tube in liquid phasemode, and the output of the 3^(rd) tube was partly combined with thefeed to the first tube. The postreactor was operated in straight pass inliquid phase mode. 2-Methyl-4-phenyl-2-butanol (20-30 g/h; catalysthourly space velocity=0.4-0.6 kg/(L×h)) was pumped through the reactorcascade with pure hydrogen at a mean temperature of 120-180° C. in themain reactor and 140-180° C. in the postreactor, and a constant pressureof 36 bar. The conversion of 2-methyl-4-phenyl-2-butanol was 100%, theselectivity for 4-cyclohexyl-2-methyl-2-butanol 88-98%. The samples wereanalyzed by means of gas chromatography (30 m column material DB1 ID:0.25 mm, FD: 0.25 μm, 50° C.—5 min isothermal, −6° C./min→290° C.—219min isothermal). The hydrogenation was conducted over a period of 250 h,without any observable decrease in the catalyst activity.

Example 11 Mixture of 4-cyclohexyl-2-methyl-2-butanol and4-cyclohexyl-2-methyl-2-pentanol

In a 300 mL autoclave, 69 g of a mixture consisting of2-methyl-4-phenyl-2-butanol (98.2 area %) and2-methyl-4-phenyl-2-pentanol (0.6 area %) were dissolved in 95 g oftetrahydrofuran, and 2.2 g of a catalyst according to preparationexample 1 were initially charged in a catalyst basket. The autoclave waspurged three times with nitrogen. This was followed by hydrogenation at160° C. and hydrogen pressure 160 bar for 10 hours. The output wasanalyzed by means of gas chromatography (30 m column material DB1 ID:0.25 mm, FD: 0.25 μm, 50° C.—5 min isothermal, −6° C./min→290° C.—219min isothermal). The composition of the output after 10 h is reported inthe table below.

2- Methyl- 4- 4- 4- 4- Cyclohexyl- Cyclohexyl- 2-Methyl- phenyl-Cyclohexyl- 2-methyl- 2-methyl- 4-phenyl- 2- 2-methyl- 2-butanol2-pentanol 2-pentanol butanol butane Comp. 97.4% 0.5% 0.0% 0.0% 1.7% 10h [area%]¹⁾ ¹⁾Composition of the output after 10 h

After distillative removal of 4-cyclohexyl-2-methylbutane, a mixture of4-cyclohexyl-2-methyl-2-butanol and 4-cyclohexyl-2-methyl-2-pentanol wasobtained, which differed from the pure substance4-cyclohexyl-2-methyl-2-butanol especially by an additional,advantageous, slight flowery note.

Example 12 4-Cyclohexyl-2-methyl-2-pentanol

By reaction of α-methylstyrene with isopropanol under the conditionsdescribed in example 1, after multistage distillation, a mixture which2-methyl-4-phenyl-2-pentanol (90.3 GC area %) was obtained. In a 300 mLautoclave, 27.7 g of this mixture were dissolved in 132.3 g oftetrahydrofuran, and 1.6 g of a catalyst according to preparationexample 1 were initially charged in a catalyst basket. The autoclave waspurged three times with nitrogen. This was followed by hydrogenation at160° C. and hydrogen pressure 160 bar for 10 hours. The output wasanalyzed by means of gas chromatography (30 m column material DB1 ID:0.25 mm, FD: 0.25 μm, 50° C.—5 min isothermal, −6° C./min 290° C.—219min isothermal). The composition of the output after 10 h is reported inthe table below.

4-Cyclohexyl-2-methyl- 2-Methyl-4- 2-pentanol phenyl-2-pentanol Comp. 10h 85.9% 1.4% [area %]¹⁾ ¹⁾Composition of the output after 10 h

4-Cyclohexyl-2-methyl-2-pentanol by means of high-resolution massspectrometry (HRMS) and by means of ¹H NMR identified:

HRMS (GC-ToF-MS, FI):

[M-H₂O+H]+ 166,1726 (measured);

[M-H₂O+H]+ 166,1722 (calculated for C₁₂H₂₂) difference+0.0004

¹H NMR (400 MHz, d⁶-dmso): δ=4.05 (s, 1H), 2.48 (s, 2H), 0.95-1.77 (m,12H), 1.05 (s, 6H), 0.92 (d, 3H) ppm.

The invention claimed is:
 1. A process for preparing4-cyclohexyl-2-methyl-2-butanol, comprising: a) reaction of styrene withisopropanol at elevated temperature to obtain2-methyl-4-phenyl-2-butanol, and b) heterogeneously catalyzedhydrogenation of 2-methyl-4-phenyl-2-butanol over a catalyst suitablefor ring hydrogenation of aromatics.
 2. The process according to claim1, wherein the reaction in step a) is performed in the absence of acatalyst.
 3. The process according to claim 1, wherein essentially nofeedstocks other than styrene and isopropanol are used for reaction instep a).
 4. The process according to claim 1, wherein the reaction instep a) is effected under conditions under which isopropanol is in thesupercritical state.
 5. The process according to claim 1, wherein thereaction in step a) is effected at a temperature in the range from 250to 500° C. and a pressure in the range from 5 to 50 MPa.
 6. The processaccording to claim 1, wherein the molar ratio of the styrene used instep a) to the isopropanol used in step a) is in the range from 1:5 to1:200.
 7. The process according to claim 1, wherein at least 80% of theisopropanol is initially charged and at least 80% of the styrene used instep a) is fed to the reaction in step a) under reaction conditions. 8.The process according to claim 7, wherein the styrene is fed in such away that the molar ratio of the styrene present in the reaction zone tothe isopropanol present in the reaction zone during the reaction is lessthan 1:10.
 9. The process according to claim claim 1, wherein thereaction mixture obtained in step a), optionally after removal ofisopropanol, is fed directly to step b).
 10. The process according toclaim 1, wherein the reaction mixture obtained in step a) is subjectedto a distillative purification and the purified2-methyl-4-phenyl-2-butanol is supplied to step b).
 11. The processaccording to claim 1, wherein the catalyst used in step b) comprises, asan active metal, palladium, platinum, cobalt, nickel, rhodium, iridium,ruthenium, alone or together with at least one further active metal oftransition groups IB, VIIB or VIIIB of the Periodic Table of theElements (CAS version).
 12. The process according to claim 1, whereinthe catalyst used in step b) comprises, as an active metal, rutheniumalone or together with at least one further active metal of transitiongroups IB, VI IB or VIIIB of the Periodic Table of the Elements (CASversion).
 13. The process according to claim 1, wherein the catalystused in step b) is a supported catalyst which comprises, as an activemetal, ruthenium, rhodium or nickel alone or together with at least onefurther active metal of transition groups IB, VIIB or VIIIB of thePeriodic Table of the Elements (CAS version) on a support materialselected from silicon dioxide-containing and aluminum oxide-containingsupport materials.
 14. The process according to claim 1, wherein thecatalyst used in step b) is a supported catalyst which comprises, as anactive metal, ruthenium alone or together with at least one furtheractive metal of transition groups IB, VI IB or VIIIB of the PeriodicTable of the Elements (CAS version) on a support material selected fromsilicon dioxide-containing and aluminum oxide-containing supportmaterials.
 15. The process according to claim 14, in which the amount ofthe active metal is 0.1 to 1% by weight, based on the total weight ofthe catalyst.
 16. The process according to any of claim 13, wherein thecatalyst is a shell catalyst in which at least 60% by weight of theactive metal is present in the shell of the catalyst down to apenetration depth of 200 μm, determined by means of SEM-EPMA (EDXS). 17.The process according to claim 16, wherein the support material of thecatalyst has a pore volume in the range from 0.6 to 1.0 ml/g, determinedby Hg porosimetry, and a BET surface area of 280 to 500 m²/g, and atleast 90% of the pores present have a diameter of 6 to 12 nm.
 18. Theprocess according to claim 1, wherein step b) is performed in tricklemode.